Interstate 270
Interstate 270 (I-270) makes up a large portion of the outer belt freeway in the St. Louis, Missouri metropolitan area. The counterclockwise terminus of I-270 is at the junction with Interstate 55 in Mehlville, Missouri; the clockwise terminus of the freeway is at the junction with I-55 and I-70 north of Troy, Illinois. The entire stretch of I-270 is 50.59 miles (81.42 km).
Interstate 270 between Interstate 70 and Interstate 55 was formerly designated Interstate 244, a Western bypass of St. Louis, Missouri. It was originally proposed by Missouri as Interstate 144, but the road was a beltway (or part of one), so the AASHTO assigned it the number "244". By the late 1970s, the entire beltway (including today I-255) was integrated as a part of "270" for consistency. However, the politicians in Illinois started planning their supplemental freeway system in the mid 1970s and somehow a 5 mile section of "Corridor 413" was included into the Interstate Highway System in April 1978.[2] This caused a potential place of confusion in Pontoon Beach, Illinois where I-270 would have intersected itself, and eventually IDOT decided on the 255 numbering in 1980 (but not before considering renumbering a 8 mile section to I-870).
Interstate 270 between Interstate 70 and Interstate 55 was formerly designated Interstate 244, a Western bypass of St. Louis, Missouri. It was originally proposed by Missouri as Interstate 144, but the road was a beltway (or part of one), so the AASHTO assigned it the number "244". By the late 1970s, the entire beltway (including today I-255) was integrated as a part of "270" for consistency. However, the politicians in Illinois started planning their supplemental freeway system in the mid 1970s and somehow a 5 mile section of "Corridor 413" was included into the Interstate Highway System in April 1978.[2] This caused a potential place of confusion in Pontoon Beach, Illinois where I-270 would have intersected itself, and eventually IDOT decided on the 255 numbering in 1980 (but not before considering renumbering a 8 mile section to I-870).